If it hits them, it hits you. Modern tabks rely on alot of electronic equipment, from sights to targeting and other systems. Are you going to shield all of them? How much would the tabk cost? What good is all that shielding if an artillery shell or atgm can take out the tank?
Its probably a question of:
Cost
Blasting your own systems
Blasting your own comms
Can you even hear the whizzing of a drone from inside the tank?